MSpec is a specialized framework that is syntax-compatible with RSpec for basic things like describe, it blocks and before, after actions. MSpec contains additional features that assist in writing the RubySpecs used by multiple Ruby implementations. Also, MSpec attempts to use the simplest Ruby language features so that beginning Ruby implementations can run it.
Gemfile gem 'mspec', '~> 1.5.13'
install gem install mspec -v 1.5.13